Answer: b
Explanation: Benzoyl chloride
A weak band near 1750 cm-1. Since, band is of weak intensity, it must be due to fermi Resonance. So correct option is Fermi resonance between C = O band and first overtone.

3. Why ketenes absorb in IR at a very high frequency (2150 cm-1)?
a) The inner C is sp hybridized
b) The more s character in a bond, the stronger it is
c) Inner C is sp2 hybridized
d) Inner C is sp3 hybridizedView Answer

Answer: c
Explanation: Ketenes absorb in IR at a very high frequency (2150 cm-1) because inner C is sp2 hybridized. Bonds with more s character absorb at a higher frequency.

6. What is the relation between wave number of IR absorption and the reduced mass?
a) Wave number is directly proportional to reduced mass
b) Wave number is inversely proportional to reduced mass
c) Wave number is independent of the reduced mass
d) Wave number is directly proportional to square of reduced massView Answer

8. Which of the following molecules will not show infrared spectrum?
a) H2
b) HCI
c) CH4
d) H20View Answer

Answer: a
Explanation: Correct option is H2 as HH2 do not have dynamic dipole moment, so no spectrum will be observed.

9. The phosphorescence spectrum of the excited species is due to which transition?
a) Singlet to triplet transitions
b) Triplet to singlet transitions
c) Vibration modes
d) Electron spin transitionsView Answer

Answer: b
Explanation: The phosphorescence spectrum of the excited species is due to triplet to singlet transitions. In an excited singlet state, the electron is promoted in the same spin orientation as it was in the ground state (paired). In a triplet excited stated, the electron that is promoted has the same spin orientation (parallel) to the other unpaired electron.

10. Why Monomeric saturated aliphatic carboxylic acids show carbonyl stretching frequency near 1760 cm-1, while saturated aliphatic ketones near 1720 cm-1?
a) Mesomeric (M) effect is dominant in acids over the inductive (I) effect
b) I effect is dominant in carboxylic acids over the mesomeric effect
c) I effect on ketones is dominant over the M effect
d) M effect in ketones is dominantView Answer